High-Speed, low-noise millimeterwave hemt and pseudomorphic hemt

Abstract

An epitaxial structure and method of manufacture for a field-effect transistor capable of high-speed low-noise microwave, submillimeterwave and millimeterwave applications. Preferably, the epitaxial structure includes a donor layer and/or buffer layer made from a semiconductor material having the formula AlP 0 .39+y Sb 0 .61-y.

What is claimed is: 
     
       1. An epitaxial structure for a field-effect transistor comprising: a first quantum well barrier layer over a semiconductive support, said first quantum well barrier layer comprising a first wide-bandgap semiconductor material;   a channel layer over the first quantum well barrier layer, said channel layer comprising a narrow-bandgap semiconductor material;   a second quantum well barrier layer over the channel layer, said second quantum well barrier layer comprising a second wide-bandgap semiconductor material;   a barrier layer over the second quantum well barrier layer, said barrier layer comprising AlP 0 .39+y Sb 0 .61-y, wherein y has a value between about 0 and about 0.39.   
     
     
       2. The epitaxial structure of claim 1 further comprising a donor layer between the second quantum well barrier layer and the barrier layer, said donor layer comprising a third wide-bandgap semiconductor material. 
     
     
       3. The epitaxial structure of claim 1 wherein the barrier layer further comprises a first dopant. 
     
     
       4. The epitaxial structure of claim 2 wherein the donor layer further comprises a second dopant. 
     
     
       5. The epitaxial structure of claim 2 further comprising a buffer layer between the first quantum well barrier layer and the semiconductive support, said buffer layer comprising a semiconductor material. 
     
     
       6. The epitaxial structure of claim 5 wherein: said semiconductor material is AlP 0 .39+y Sb 0 .61-y, wherein y has a value between about 0 and about 0.39;   said first wide-bandgap semiconductor material and said second wide-bandgap semiconductor material are compounds selected from the group consisting essentially of AlIn 0 .48+z As 0 .52-z and AlP 0 .39+y Sb 0 .61-y, wherein z has a value between about 0 and about 0.52 and y has a value between about 0 and about 0.39;   said narrow-bandgap semiconductor material is Ga 0 .47-x In 0 .53+x As, wherein x has a value between about 0 and about 0.47.   
     
     
       7. The epitaxial structure of claim 6 wherein the semiconductive support comprises an InP substrate. 
     
     
       8. An epitaxial structure for a field-effect transistor comprising: a buffer layer over a semiconductive support, said buffer layer comprising AlP 0 .39+y Sb 0 .61-y, wherein y has a value between about 0 and about 0.39;   a first quantum well barrier layer over the buffer layer, said first quantum well barrier layer comprising a first wide-bandgap semiconductor material;   a channel layer over the first quantum well barrier layer, said channel layer comprising a narrow-bandgap semiconductor material;   a second quantum well barrier layer over the channel layer, said second quantum well barrier layer comprising a second wide-bandgap semiconductor material;   a barrier layer over the second quantum well barrier layer, said barrier layer comprising a wide-bandgap semiconductor material.   
     
     
       9. The epitaxial structure of claim 8 further comprising a donor layer between the second quantum well barrier layer and the barrier layer, said donor layer comprising a third wide-bandgap semiconductor material.